Transition from disc to rod-like shape of 16-3-16 dimeric micelles in aqueous solutions

Abstract

Small-angle neutron scattering (SANS) measurements from bis-cationic C₁₆H₃₃N⁺(CH₃)₂– (CH₂)₃–N⁺(CH₃)₂C₁₆H₃₃ 2Br^- dimeric surfactant, referred to as 16-3-16, at different concentrations and temperatures, are reported. It is seen that micelles are disc-like for concentrations C=2.5 and 10 mM at temperature T=30°C. At low concentration C=0.5 mM micelles are rod-like. Similarly, there is a disc to rod-like transition of micelles on increasing the temperature. For C=2.5 mM, micelles are rod-like at T=45 and 70°C.

References

1. V. Degiorgio and M. Corti, Physics of Amphiphiles: Micelles, Vesicles and Microemulsions, North-Holland, Amsterdam, 1985.
2. Y. Chevalier and T. Zemb, Rep. Prog. Phys., 1990, 53, 279.
3. F. M. Menger and C. A. Littau, J. Am. Chem. Soc., 1991, 113, 1451.
4. R. Zana, M. Benrraou and R. Rueff, Langmuir, 1991, 7, 1072.
5. M. J. Rosen, CHEMTECH., 1993, 23, 30.
6. S. De, V. K. Aswal, P. S. Goyal and S. Bhattacharya, J. Phys. Chem., 1996, 100, 11 664.
7. V. K. Aswal, S. De, P. S. Goyal, S. Bhattacharya and R. K. Heenan, Phys. Rev. E, 1998, 57, 776.
8. S. S. Berr, J. Phys. Chem., 1987, 91, 4760.
9. P. S. Goyal, B. A. Dasannacharya, V. K. Kelkar, C. Manohar, K. S. Rao and B. S. Valaulikar, Physica B, 1991, 174, 196.
10. R. K. Heenan and S. M. King, in Proceedings of the International Seminar on Structural Investigations at Pulsed Neutron Sources, Dubna, 1992, ed. V. L. Aksenov, A. M. Balagurov and Y. V. Taran, JINR, Dubna, 1993.
11. J. B. Hayter and J. Penfold, Coll. Polym. Sci., 1983, 261, 1022.
12. A. Guinier and G. Fournet, Small Angle Scattering of X-rays, Wiley, New York, 1955.
13. S. H. Chen, Annu. Rev. Phys. Chem., 1986, 37, 351.
14. P. S. Goyal, Phase Transitions, 1994, 50, 143.
15. J. N. Israelachvili, D. J. Mitchell and B. W. Ninham, J. Chem. Soc., Faraday Trans. 2, 1976, 72, 1525.